A forum for owners of Yamaha TTR250 trail and enduro bikes!

Good question, Brett.

It looks like you may well be in a position, soon, to let us all know?

There has been some past discussion on what clamps and forks from which model can be utilised BUT I don't thing a definitive answer has been found.

Maybe now it will be?

Martyn

Rober Denison fitted a pair of Showa USD forks on his TTR that came off a 2006 Kawasaki KX250F. He said that they took a little work to fit, ie special modified KX yoke spindle, special modified TTR wheel spindle, and front caliper mount modified to take TTR calliper. He then took the forks apart and fitted softer springs.

He also said "To be honest the original forks were great but these offer a bit more in the way of setting up and adjustment. It’s a fair bit of work to do this mod – not one for the faint hearted (I manage a machine shop!). They do look the business though!

Pics below:

I have been watching parts on ebay for a while, don't recall seeing a whole front end but once. Parting out a whole bike may be a good way to get everything at once, seems like there is a whole industry of parting stuff out & selling online.

I have a set of YZ triple clamps I bought in a moment of weakness for this same project. Haven't fooled with them yet on the bike but I can measure the stem, etc. if you need any info. I believe they were off an '09.

From my research regarding the wheel, a WR/YZ has a 20x37x9 front wheel bearing (so I assume 20mm axle, don't know what the actual mounting point diameter is).

Could the TTR axle be used with end sleeves, if it's long enough?

I have done some preliminary Googling etc and findings are detailed below. If anyone can fill in any of the blanks or improve on the data then please contribute.

YZ v TTR250 fork information

Fork Dimensions & Stroke

There are two fork diameters for the YZ Forks 46mm and 48mm (Standard TTR is 42mm)

Fork Lengths are TTR = ?" and the YZ = 37"

Need comparative figure for the TTR250

YZ Forks

Length - Top of upper yoke to axle centre 825 mm 890 mm 925 mm

Length – Bottom of steering Head to axle centre 615 mm 678 mm

Fork Travel or Stroke 170 mm 210 mm 280 mm

Need comparative figures for the TTR250

YZ Yoke Post Lengths

There are different lengths of fork yoke posts between the different year models of the YZ, this has meant the need for spacers of different lengths above the upper Steering Head Bearings (SHB) on some conversions.

 "Short" - 98-08 YZ125 & YZ250F & 98-05 WR250F           Length 195 mm ?

“Mid” - 2008 YZ450F                                                       7 mm longer

"Long" - 98-07 YZ250 & YZ400F thru 450F & WR450F      12 mm longer

Steering Head Bearings

Yamaha use 2 bearing sizes, Top – 28x52mm, Bottom - 30x52mm

 Need comparative figures for the TTR250

YZ SHB Suppliers

Need comparative figures for the TTR250

Pivot Works Kit Part Number PWSSK-Y05-421

Part Number      Qty       Component Description

Y-BE-105          1          Bearing - 28.00 x 52.00 x 16.40 Cone

Y-BE-106          1          Bearing - 29.98 x 52.00 x 15.95 Cone

Y-SE-105          1          Seal - 28.50 x 60.50 x 4.15

For Models:

2001-2009 Yamaha WR 250F, 2000 Yamaha WR 400F, 2001-2002 Yamaha WR 426F

2003-2009 Yamaha WR 450F, 2000-2009 Yamaha YZ 125, 2000-2009 Yamaha YZ 250

2001-2009 Yamaha YZ 250F, 2000-2002 Yamaha YZ 426F, 2003-2009 Yamaha YZ 450F

All Balls Kit 22-1001 Bearings 1 x 28x52x16 1 x 30x52x16

All Balls have a choice on bearing height for the lower bearing

99-3513             28 mm 52 mm 16 mm

99-3521             30 mm 52 mm 16 mm

99-3504             30 mm 52 mm 17 mm

The fork post is a press fit in the yoke so it should be easy enough to replace the YZ post with it except that the YZ posts appear to be either 28mm or 30mm in diameter  

This thread is also interesting, a bit old but but relates to the earlier design, pre-SSS:    http://www.thumpertalk.com/topic/363979-introducing-the-kyb-phase-4-fork/

I think it is the same kit for more late-model WR's

This video (there are 2 parts) also gives you a good idea of the newer stlye:  http://www.rockymountainatvmc.com/Video/91

That's brilliant Ted - very many thanks!

It seems to me that the best way forward would be to open up the hole in the YZ lower fork clamp to 33mm to accept the TTR post which will need to be pressed in.

If I am right then the TTR steering head bearings are all going to fit and the YZ top clamp will also fit straight on as it has the same diameter.

Have I missed something or is it that simple 

Brian

One other consideration in swapping to the TTR stem spacing (distance between upper & lower clamps) is that the upper fork tubes taper to a smaller diameter between the areas where they are clamped by the triples. You can see it in the second photo you posted of the Showas & also in the linked pic of some YZ forks.  There is likely enough mounting surface for the smaller spacing but is probably worth checking.

Just to futher confuse things, I came across this:

The Aussies here probably already know about this, but Geoff Ballard (who you Brits may know more about than I do) runs TTR forks on his WR.

Check out the reducers to hold the much smaller upper tubes.

TTRfan wrote:

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Makes you think doesn't it!

A great vid and a lovely man.

I found a quote from him and like him even more now:

For the adventure stuff, I'll stick with my favourite tools. And for the big stuff, it's the GS1200 Adventure; I still think it's the king! On the smaller, and more go anywhere side of things, I think I'll forever have a Yamaha TTR250 in the shed! For the 'all round' and tighter stuff, you can't kill or beat that thing. Last month I did my sixth straight New Zealand Safari, where I rode a TTR. I love them – and that ride in NZ – so much that I've bought one that I leave over there at a mates place. That bike is definitely under rated!

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It does indeed make you think.

I thought maybe I'd find mention of what modifications they do to the TTR forks but haven't found anything. Sounds as though they were using the TTR front ends on occasion as recently as a year ago.

Like the quote as well.

the bike with the yellow frame and the usd forks that is !!!!

I dug the USD forks out & took few numbers for the conversion

into the TTR.... It turns out the 05 YZF250 USD forks use the same

ID bearings as the TTR... 28mm Top / 30mm bottom...

Even the steering stops look to be in about the right place..

The YZF forks are 40mm longer but theres enough un-tapperd

area where the bottom clamp fits to raise them 30mm... top

is no issue as there lonf un-tappered area..

not looked at the wheel & caliper yet... but the YZF dose use a

20mm axle... so spacer sleeves will be need to reduce the

holes in the forks to 17mm....

also got a small speedo/tach as I wont be able to use the TTR

speedo drive...

the pics.....

I think all that changing forks from other bikes is a huge waste of time, the TTR forks are pretty good and can be made excellent by any good suspension tuner, here in Oz we have for example Teknik Racing, they are suspension experts for less than $500 you get your TTR forks converted into fantastic forks, gold valves, cartridge emulators, new springs, seals etc...

That would be my first option with out a doubt. $1000 get both ends done, no mucking around all in 1 day.

Cheers, Steve

Luck is on your side Pete!

Here is a page of sizes of all thinks fork related -  http://www.clubchopper.com/forums/metric-chopper-talk/77043-jap-bikes-fork-tube-sizes-neck-bearings-axle-diameters.html

Might be useful to someone